Cationic copper (I) complexes with bulky 1,4-diaza-1,3-butadiene ligands – Synthesis, solid state structure and catalysis

• Published in: Journal of molecular structure 2013-05, Vol.1040, p.129-138
• Main Authors: Anga, Srinivas, Kottalanka, Ravi K., Pal, Tigmansu, Panda, Tarun K.
• Format: Article
• Language: English
• Subjects: 1,4-Diaza-1,3-butadiene; acetylene; catalysts; catalytic activity; condensation; copper; Copper(I); Coupling reaction; Homoleptic complex; Metallacycle; methylene chloride; X-ray diffraction
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2013.02.037

•Two bulky 1,4-diaza-1,3-butadiene ligands were synthesized.•Ligand 2 formed homoleptic and ligand 3 formed heteroleptic copper(I) complexes.•Solid state structures of all the ligand s 2-3 and copper(I) complexes 3-5 were established.•Complexes 3-5 were tested as catalyst for the coupling reaction of o-iodophenol and phenyl acetylene. We report the full characterization of two glyoxal-based ligands N,N bis(diphenylmethyl)-1,4-diaza-1,3-butadiene ligand (DADPh2, 1) and more bulky N,N bis(triphenylmethyl)-1,4-diaza-1,3-butadiene ligand (DADPh3, 2) by the condensation reaction of glyoxal and diphenylmethanamine and triphenyl-methanamine respectively. The copper (I) complex of composition [Cu(DADPh2)2]PF6 (3) having two neutral bidentate N,N bis(diphenyl-methyl)-1,4-diaza-1,3-butadiene ligand was prepared by the reaction of [Cu(CH3CN)4]PF6 and 1 in 1:2 ratio in dichloromethane. In a similar reaction with N,N bis(triphenylmethyl)-1,4-diaza-1,3-butadiene ligand (2) and [Cu(CH3CN)4]PF6 in dichloromethane yielded corresponding heteroleptic copper (I) complex [Cu(DADPh3)(CH3CN)2]PF6 (4). Another copper (I) complex [Cu(DADPh2)(PPh3)]PF6 (5) can also be obtained by the one pot reaction involving ligand 1, [Cu(CH3CN)4]PF6 and triphenylphosphine. Solid state structures of all the five compounds were established by single crystal X-ray diffraction analysis. The solid state structures of the copper complexes 3–5 reveal a distorted tetrahedral geometry around the copper (I) centers. The copper complexes 3–5 were tested as catalysts for the coupling reaction of o-iodophenol and phenyl acetylene and it was observed that complex 4 exhibits the highest catalytic activity.